I'm a computer tech and have tried loads of security suites. Emsisoft Anti-Malware is a terrific Windows security suite, well worth having in freeware mode as a backup to your main one (but not running all the time in conflict with your main one) to scan occasionally for stuff your main one misses.
In paid mode it would be hard to find a better one. Well worth $16.
They also have a good referral program - 1 month for a friend that installs the free one, 6 months if they buy (probably couldn't be linked to this promo).
Or you can use Malwarebyte's Anti-Malware for free, which does just as good a job of detection and a better job of removal. It's the scanner of choice on reputable tech-help sites such as MajorGeeks and BleepingComputer.
http://www.filehippo.com/download_malwarebytes_anti_malware/